THz Absorption Spectroscopy of a Liquid via a Polarity Probe. A Case Study of Trehalose/Water Mixtures

 From the time-resolved Stokes shift R(t) of N-Methyl-6-Quinolone fluorescence, on 0.100-100 ps time scales, the frequency-dependent permittivity e(w) of the surrounding medium is extracted up to about 100 cm^-1. The key consists in an appropriate analytical connection e(w) ® R(t) which is needed for data fitting. Measurements with bulk trehalose/water solutions serve to establish and test the method. Its unique feature is locality, i.e. the possibility to measure e(w) around a supramolecular structure with a covalently connected or embedded probe.

M. Sajadi, Y. Ajaj, I. Ioffe, H. Weingärtner, N. P. Ernsting